Silicone pressure sensitive adhesive containing alkylmethylsiloxane wax and related methods and devices

ABSTRACT

Hot-melt silicone pressure sensitive adhesive compositions containing alkylmethylsiloxane waxes, methods of using the compositions and devices made using the compositions are disclosed. The hot-melt silicone pressure sensitive adhesive compositions include a mixture of (i) a silicate resin, (ii) a silicone fluid, and (iii) an alkylmethylsiloxane wax having a melting point of between 30° C. and 70° C. The alkylmethylsiloxane wax decreases dynamic viscosity of the adhesive at temperatures ranging from about 50° C. to about 200° C.

TECHNICAL FIELD

The present invention relates to hot-melt silicone pressure sensitiveadhesive compositions containing alkylmethylsiloxane wax, methods ofusing the composition, and devices made using the composition.

BACKGROUND OF THE INVENTION

A pressure sensitive adhesive, generally, is a material which adheres toa surface with slight pressure and releases from the surface withnegligible transfer of the material to the surface. Silicone pressuresensitive adhesives that are known in the art are typicallysolvent-based adhesives. The solvents are employed primarily to reducethe dynamic viscosity of the silicone pressure sensitive adhesive to adynamic viscosity which is easily coated onto the substrate of choice,and the solvents are removed after coating. As with any solvent-basedpressure sensitive adhesive (PSA), special precautions must be taken tocontain and avoid environmental exposure of the solvents and avoidflammable and explosive conditions as many of the solvents used areflammable.

Hot-melt pressure sensitive adhesives are those adhesives, which uponheating, melt to viscosities suitable for coating, but when cooled aregenerally in a flowless state. Hot-melt pressure sensitive adhesivesexhibit the following advantages over solvent-based pressure sensitiveadhesives. Hot-melt pressure sensitive adhesives: (1) do not requireremoval and containment of solvents; (2) due to the absence of flammablesolvents, do not require special precautions to avoid fires; (3) makeavailable coating processes other than those commonly used withsolvent-based pressure sensitive adhesives; and (4) are more easilycoated into thick sections with minimal bubbling, a problem which oftenresults with coating out solvent-based PSA's. In addition, hot-meltPSA's have the advantage of not containing solvents which sometimesinterfere with the addition of other ingredients to the PSA.

Silicone pressure sensitive adhesives are preferred over other types ofPSA's in many applications, especially in the medical area. For example,because silicone pressure sensitive adhesives are acceptable for topicaluse, they have found use in transdermal drug delivery applications whichinvolve the adherence of a drug-containing patch to a patient's skin.

U.S. Pat. No. 4,865,920 to Randall P. Sweet, discloses a method ofmaking hot-melt silicone pressure sensitive adhesives which have theinherent benefits of being composed of silicone and being a hot-meltPSA. In U.S. Pat. No. 4,865,920, the hot-melt silicone pressure adhesivecomposition consists of (i) a silicate resin; (ii) a silicone fluid; and(iii) 1 to 10 weight percent, based on the total weight of the silicateresin and silicone fluid, of an ester having the formula: R--C(O)OR'wherein R is a monovalent hydrocarbon radical having from 2 to 32 carbonatoms and R' is a monovalent hydrocarbon radical having from 1 to 14carbon atoms.

Although this silicone pressure sensitive adhesive composition has beenfound to be highly efficacious, it would be desirable to includeadditives which will decrease dynamic viscosity to improve thecoatability of the hot-melt adhesive at temperatures at or below 200° C.

It would also be desirable for the adhesive to be compatible with avariety of release liners. The new hot-melt silicone pressure sensitiveadhesive must allow permeation of lipophilic drugs through the PSA.Also, the adhesive should have controllable adhesion, so that theaggressiveness of adhesion can be tailored to the application.

Therefore, it is a primary object of the present invention to teach acomposition for a silicone pressure sensitive adhesive which includes analkylmethylsiloxane wax in combination with a silicate resin and asilicone fluid which will decrease the dynamic viscosity of the adhesiveso that coating is easier to achieve.

It is another object of the present invention to provide a method forcoating the wax-containing pressure sensitive adhesive onto a substrate.

It is yet another object of the present invention to provide devices,including matrix-type and reservoir-type transdermal drug deliverydevices, which include the above described adhesive.

SUMMARY OF THE INVENTION

This invention provides a hot-melt pressure sensitive adhesivecomposition which is formed of materials which are highly acceptable intopical applications. The hot-melt silicone pressure sensitive adhesivecompositions of this invention contain an alkylmethylsiloxane wax whichrenders the adhesive less viscous at temperatures up to about 200° C.and therefore improves adhesive coatability over the prior art siliconePSA's and the hot-melt PSA of U.S. Pat. No. 4,865,920. The inventionalso provides a means of controlling the pressure sensitive adhesiveproperties of tack, adhesion, and release of the composition.

The hot-melt silicone pressure sensitive adhesive composition comprisesa mixture of (i) a silicate resin and (ii) a silicone fluid, the mixtureexhibiting tackiness and adhesiveness, the mixture being blended with(iii) an alkylmethylsiloxane wax which decreases the dynamic viscosityof the adhesive at the temperatures used for coating the adhesive onto asubstrate. Improved adhesive coatability minimizes waste of materialsduring manufacture and expedites production. This results in costsavings and increases profits. The invention also encompasses methods ofusing the composition, and devices made using the compositions.

Further disclosed, are matrix-type and reservoir-type transdermal drugdelivery devices for bioactive agents. The matrix-type drug deliverydevice includes a backing substrate, a matrix on top of at leastportions of the backing substrate, the matrix including the hot-meltsilicone pressure sensitive adhesive which includes thealkylmethylsiloxane wax, along with the drugs, excipients, enhancers,co-solvents or mixtures thereof. The adhesive matrix is coated on to thebacking substrate and covered with a release liner in order to aid inhandling. A reservoir-type delivery device includes a backing substrate,the liquid or solid reservoirs on top of the backing substrate, thereservoir including the drugs to be transferred, a layer of adhesive ontop of the reservoir, and finally a release liner.

These and other objects and advantages of the invention will become moreapparent from a detailed description thereof which follows.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 shows a matrix-type delivery device for a bioactive agent or drugin place within a transdermal patch;

FIG. 2 shows a liquid reservoir-type transdermal drug delivery device;and

FIG. 3 shows a solid state reservoir-type transdermal drug deliverydevice.

DETAILED DESCRIPTION OF THE INVENTION

Generally, the hot-melt compositions made in accordance with the presentinvention are composed of a silicone pressure sensitive adhesivecontaining (i) a silicate resin present in an amount between about 30 toabout 70 percent by weight based on total composition weight, (ii) asilicone fluid present in an amount between about 22 to about 60 percentby weight based on total composition weight, and (iii) analkylmethylsiloxane wax present in an amount between about 1.0 to about25.0 percent by weight based on total composition weight.

The following paragraphs disclose acceptable and preferable siliconepressure sensitive adhesives which may be combined with the disclosedalkylmethylsiloxane waxes to provide an improved hot-melt adhesivecombination with decreased dynamic viscosity. This improved adhesive maybe used, in turn, to form improved devices for many applicationsincluding transdermal drug delivery patches and other medicalapplications which do not require solvents for coating the adhesive.

As mentioned above, hot-melt PSA's are preferred over previouslyavailable adhesives because solvents are not required to coat theadhesive on a substrate (e.g. a bandage or patch). It appears that theaddition of alkylmethylsiloxane waxes to a basic PSA formulation helpsto decrease dynamic viscosity and allows it to be hot melt coated. Thismeans that the coatability of the PSA in the absence of solvents isimproved, and better devices can be made. One of ordinary skill in theart will clearly see the advantages of the present invention.

I. SUITABLE SILICONE PRESSURE SENSITIVE ADHESIVES

One suitable class of pressure sensitive adhesives to be employed in thehot-melt compositions of this invention consists of a mixture of

(i) a trimethylsilyl-endblocked polysilicate resin such as a silicateresin, consisting of a benzene-soluble resinous copolymer containingsilicon-bonded hydroxyl radicals and consisting essentially oftriorganosiloxy units of the formula R₃ SiO_(1/2) and tetra functionalsiloxy units of the formula SiO_(4/2) in a ratio of about 0.6 to 0.9triorganosiloxy units for each tetra functional siloxy unit present inthe copolymer, wherein each R is a monovalent alkylmethylsiloxaneradical independently selected from the group consisting of hydrocarbonradicals of from 1 to 6 inclusive carbon atoms; and

(ii) a silanol-endstopped polydiorganosiloxane fluid, e.g. apolydimethylsiloxane fluid. U.S. Pat. No. 2,736,721 to Dexter, et al.and U.S. Pat. No. 2,814,601, to Currie, et al. are hereby incorporatedby reference to teach of such or similar pressure sensitive adhesivecompositions.

Another class of suitable pressure sensitive adhesives for use incombining with the alkylmethylsiloxane wax according to the presentinvention is that or those similar to U.S. Pat. No. 2,857,356, toGoodwin, Jr., which is hereby incorporated by reference. The Goodwin,Jr. patent teaches silicone pressure sensitive adhesives which consistof a mixture of ingredients comprising (i) a cohydrolysis product of atrialkyl hydrolyzable silane and alkyl silicate, wherein thecohydrolysis product contains a plurality of silicon-bonded hydroxygroups, and (ii) a linear, high dynamic viscosity organopolysiloxanefluid containing silicon-bonded hydroxy groups.

To practice the present invention the silicate resin (i) and thesilicone fluid (ii) may optionally be condensed together according to aprocedure such as the procedure described in Canadian Patent 711,756 toPail, which patent is hereby incorporated by reference. In such acondensation reaction, the silicate resin (i) and the silicone fluid(ii) are mixed together in the presence of a catalytic amount of asilanol condensation catalyst, and then the silicate resin (i) and thesilicone fluid (ii) are condensed, for example, by heating under refluxconditions for 1 to 20 hours. Examples of silanol condensation catalystsare primary, secondary, and tertiary amines, carboxylic acids of theseamines and quaternary ammonium salts.

Another class of suitable pressure sensitive adhesives to use incombination with the alkylmethylsiloxane waxes are those compositionsdescribed in U.S. Pat. Nos. 4,591,622 and 4,584,355 to Blizzard et al.,U.S. Pat. No. 4,585,836 to Homan et al., and U.S. Pat. No. 4,655,767 toWoodard et al., which patents are also hereby incorporated by reference.Generally, these pressure sensitive adhesives consist of a blend of (i)a silicate resin and (ii) a silicone fluid which are chemically treatedto reduce the silicone bonded hydroxyl content of the blend. Theseadhesives may optionally be condensed as described immediately aboveprior to the chemical treatment.

Typically, the most practical pressure sensitive adhesive to combinewith an alkylmethylsiloxane wax contains at least 100 ppm silanolradicals and preferably between about 200 ppm and 1,200 ppm of silanolradicals, and includes a silicate resin combined with a silicone fluidas described above. The silicate resin preferably has a molecular weightranging from about 3500 to about 7000, and is employed in amounts fromabout 30 to about 70 percent by weight based on the total resultantcomposition of the silicone pressure sensitive adhesive. The siliconefluid is preferably employed from about 22 to about 60 percent byweight, wherein the total parts of the silicate resin and the siliconefluid equal 100 percent. It is usually preferred that the ratio ofsilicate resin to silicone fluid is between about 2:3 and about 3:7.

The silicone pressure sensitive adhesives used in this invention are notconsidered to be "silicone rubbers", which generally refer to non-tackyvulcanized rubbers. The most common type of silicone rubber consists ofa mixture of a polydimethylsiloxane gum, a filler (such as fumed silicaor other inorganic, non-resinous material), or a crosslinker, andoptionally, a catalyst. On the other hand, the silicone pressuresensitive adhesives employed in this invention are tacky (or sticky) tothe touch without the addition of plasticizers and typically adhere to asubstrate after mild pressure is applied. The silicone pressuresensitive adhesives may be cured or "rubberized" after being mixed witha cohesive strengthening agent as discussed below. However, even aftercuring, the silicone pressure sensitive adhesive composition remainstacky.

The process of curing or crosslinking silicone pressure sensitiveadhesives is known in the art. For example, see "Silicone PressureSensitive Adhesives" by D. f. Merrill in the Handbook Of PressureSensitive Adhesive Technology, edited by D. Satas (Van NostrandReinhold, Florence, Ky., 1982), pages 344-352 and "Formulating SiliconePressure Sensitive Adhesives For Application Performances" by L. A.Sobieski in Making It Stick in '86, Advances In Pressure Sensitive TapeTechnology, seminar proceedings (Pressure Sensitive Tape Council,Deerfield, Ill., 1986), pages 1-5, both sources being herebyincorporated by reference.

Generally, however, for drug delivery applications, the siliconepressure sensitive adhesive compositions are not crosslinked becauseeither (1) the crosslinking temperature is too high for the drugs or (2)the additives needed for crosslinking are non-biocompatible ingredients.A silicone pressure sensitive adhesive composition is generallyconsidered not crosslinked if it can be dissolved in a solvent.

Another difference between silicone pressure sensitive adhesivessuitable for use in the present invention and silicone rubbers, whichare unsuitable, lies in the fact that silicone pressure sensitiveadhesives are usually fillerless or contain low amounts, e.g., less thanabout 5 weight %, of fillers, such as fumed silica or other inorganicreinforcing fillers known in the silicone art. On the other hand,silicone rubbers typically contain about 15-35 weight % filler. Fillersare usually not desired in high quantities in silicone pressuresensitive adhesives, because high quantities often cause the siliconepressure sensitive adhesives to lose tack and adhesiveness and toincrease in dynamic viscosity, making it more difficult to apply acoating of the silicone pressure sensitive adhesive.

The silicone PSA's described above are all suitable for combining withcertain alkylmethylsiloxane waxes, as described in the followingparagraphs. These alkylmethylsiloxane waxes, when combined with thePSA's provide adhesives which exhibit decreased dynamic viscosity, andimproved coatability without solvents.

II. THE ALKYLMETHYLSILOXANE WAXES

The alkylmethylsiloxane waxes suitable for use in the present inventioninclude waxes having the following formulations:

    (RMeSiO).sub.x

wherein R is C_(n) H_(2n+1), Me is CH₃, 14≦n≦28, and X is an integerfrom 4 to 6;

    RMe.sub.2 SiOSiMe.sub.2 R

wherein Me is CH₃, R is C_(n) H_(2n+1), and n≧18;

    RMe.sub.2 SiOSiMe.sub.3

wherein Me is CH₃, R is C_(n) H_(2n+1), and n≧24;

    RMeSi(OSiMe.sub.3).sub.2

wherein Me is CH₃, R is C_(n) H_(2n+1), and n≧24;

    Me.sub.3 SiO(RMeSiO).sub.x (R'MeSiO).sub.y SiMe.sub.3

wherein Me is CH₃, R is C_(n) H_(2n+1), and n≧18, R' is H or C_(n)H_(2n+1) and n≧1, when R' is H or CH₃ then the ratio of X:Y is greaterthan 1:3;

    RSiO.sub.3/2

wherein R is C_(n) H_(2n+1), and n≧1;

and mixtures thereof.

The alkylmethylsiloxane waxes of the present invention have a meltingpoint of between about 30° C. and about 70° C.

Preferably, the alkylmethylsiloxane wax is added in an amount betweenabout 1.0 and about 25.0 percent by weight based on total compositionweight. Best results are noted when the wax is utilized in an amountbetween about 5 percent and about 15 percent by weight based on totalcomposition weight.

The alkylmethylsiloxane wax functions to decrease the dynamic viscosityof the hot-melt pressure sensitive adhesive at temperatures equal to orless than 200° C. Desirable dynamic viscosities of the wax-containingadhesives at temperatures equal to or less than 200° C. are less than orequal to 800 poise. The wax is particularly effective at temperatures ofbetween about 85° C. and 200° C. to improve the coatability of theadhesive onto a substrate. This effect is shown in Table 2.

The hot-melt silicone pressure sensitive adhesive compositions describedherein are prepared by mixing (i) silicate resin and (ii) silicone fluidwith (iii) the alkylmethylsiloxane wax at a temperature of at least 85°C. Alternatively, the wax may be dissolved in solvent added to thesilicate resin and silicone fluid mixture and thereafter the solvent maybe removed from the mixture. The hot-melt silicone pressure sensitiveadhesive compositions are then heated to a coatable dynamic viscosity,to temperatures of between about 85° C. and 200° C., and coated on asubstrate. The adhesive coated substrate is then cooled until it is in anon-flowing state.

A method of coating a hot-melt, alkylmethylsiloxane wax-containing,silicone pressure sensitive adhesive composition onto a substrateincludes first preparing the hot-melt silicone pressure sensitiveadhesive by mixing together (1) a silicate resin, (2) a silicone fluid,and (3) an alkylmethylsiloxane wax present in an amount between about 5and about 15 percent by weight based on total adhesive compositionweight, which decreases dynamic viscosity of the resultant hot-meltadhesive at temperatures, ranging from about 50° C. to about 200° C.Thereafter, the mixture is heated to a coatable temperature of betweenabout 85° C. and 200° C., and coated onto a substrate.

The hot-melt silicone pressure sensitive adhesive compositions may becoated onto the substrate, or other backing, by using any conventionalmeans, such as roller coating, dip coating, extrusion, knife coating, orspray coating. Although the hot-melt silicone pressure sensitiveadhesive compositions of the invention are preferably adhered to abandage or patch for medical applications, they will also adhere to manysubstrates, such as paper, cloth, glass cloth, silicone rubber,polyethylene, polyethylene terephthalate, polytetrafluoroethylene,glass, wood, metals, and skin. After coating, the PSA is cooled until itis in a non-flowing state. The alkylmethylsiloxane waxes used in thismethod are those listed hereinabove. The preferred weight percents ofthe components were also described above.

Therefore, the following suggested uses and examples should not be usedto limit the invention. Depending on the desired use, it may bedesirable to apply adhesion promoters on the substrate surface uponwhich the hot-melt silicone pressure sensitive adhesive composition willbe placed.

III. DEVICES UTILIZING ADHESIVE

The hot-melt silicone pressure sensitive adhesive compositionscontaining alkylmethylsiloxane waxes as taught by this invention areespecially suitable for assisting in delivering a bioactive agent, suchas a drug, to a bioactive agent-accepting substrate, such as a patient'sskin. The hot-melt silicone pressure sensitive adhesive compositions ofthis invention may be employed in three types of bioactive agentdelivery modes.

The first mode is a matrix-type of delivery device for a bioactive agentor drug. As shown in FIG. 1, device 10 comprises at least three layers,including a backing substrate 12 which may be permeable or occlusive towater vapor transmission from skin; a matrix 14, which is between about1 and 15 mils thick, atop at least portions of the backing substrate andcontaining a silicone pressure sensitive adhesive which includes thealkylmethylsiloxane wax, and additionally including drugs, excipients,enhancers, co-solvents 16 or mixtures thereof, said adhesive beingcompatible with the drugs, excipients, enhancers and co-solvents; and apressure sensitive adhesive release liner 18.

The matrix-type transdermal drug delivery device as shown in FIG. 1 mayinclude various drugs selected from the group consisting ofcardiovascular agents, antiarrhythmic agents, antianginal agents,antibiotics, antifungals, antimicrobials, antihypertensives, analgesics,local anesthetics, contraceptives, hormonal supplements, anti-smokingagents, appetite suppressants, hypnotics, anxiolytics and mixturesthereof.

The matrix-type transdermal drug delivery device may also includeco-solvents, enhancers and excipients as described above. Thesecompounds may be selected from the group consisting of fatty acidesters, polyols, surfactants, terpenes, glycerol esters, polyethyleneglycol esters, amides, sulfoxides, lactams, nonionic surfactants,sorbitan esters, and mixtures thereof.

As shown in FIG. 2, the second mode of delivery is a reservoir-typetransdermal drug delivery tape device. FIG. 2 shows a liquid-containingreservoir-type drug delivery device, generally denoted as numeral 20,which comprises a minimum of five layers from top to bottom. The firstlayer 22 is a backing substrate. The second layer includes a liquidreservoir 24 which may contain bioactive agents or other compositionsselected from the group consisting of drugs, enhancers, excipients andco-solvents and mixtures thereof. The third layer 26 is a ratecontrolling membrane positioned such that the reservoir 24 is sealedbetween the backing substrate 22 and the rate controlling membrane 26.This membrane acts as the rate controlling mechanism for the delivery ofthe liquid from the reservoir 24 to the patient. The fourth layer 28 isa hot-melt, alkylmethylsiloxane wax-containing pressure sensitiveadhesive coated on top of the previous layers, and the adhesive shouldbe compatible with any of the drugs, excipients, enhancers, andco-solvents present in the liquid reservoir. Appropriatealkylmethylsiloxane waxes for this device are described hereinabove. Thefifth layer 30 is a release liner attached on top of the adhesive layer,averaging between about 1 and 15 mils thick and preferably between about1 and 3 mils thick.

After removing the release liner, this device may be adhered to asurface, such as a patient's skin. Once in place, the device 20 allowsthe bioactive agent of liquid reservoir 24 to pass from the reservoirthrough the attached rate controlling membrane 26 and adhesive layer 28into the skin of the patient. The reservoir 24 of the transdermal drugdelivery device may include drugs selected from the group consisting ofcardiovascular agents, antiarrhythmic agents, antianginal agents,antibiotics, antifungals, antimicrobials, antihypertensives, analgesics,local anesthetics, contraceptives, hormonal supplements, anti-smokingagents, appetite suppressants, hypnotics, anxiolytics and mixturesthereof.

The adhesive layer of the liquid reservoir-type transdermal drugdelivery device may include the co-solvents, enhancers and excipientswhich are selected from the group consisting of fatty acid esters,polyols, surfactants, terpenes, glycerol esters, polyethylene glycolesters, amides, sulfoxides, lactams, nonionic surfactants, sorbitanesters, and mixtures thereof.

The third mode of delivery is a solid state reservoir transdermal drugdelivery device denoted by numeral 40, shown in FIG. 3. This deviceincludes a first layer 42 which is a backing substrate. The second layerconstitutes a solid reservoir 44 which may contain one or more bioactiveagents or other compositions selected from the group consisting ofdrugs, excipients, enhancers, and co-solvents indicated as 46. The thirdlayer is a hot-melt alkylmethylsiloxane wax-containing pressuresensitive adhesive layer 48 which is compatible with the drugs,excipients, enhancers and co-solvents contained therein. Again,appropriate alkylmethylsiloxane waxes for this device are describedhereinabove.

The pressure sensitive adhesive layer of this solid state deviceaverages between about 1 and 15 mils thick, and preferably is between 1and 3 mils thick. The fourth layer is a release liner 50. If desired, anadditional layer (not shown) comprising a rate controlling membrane maybe positioned between the solid reservoir 44 and the PSA 48. The solidreservoir 44 may contain drugs as described above for the liquidreservoir device of FIG. 2.

The following examples of the invention are meant to be illustrativeonly and should not be construed as limiting the invention which isproperly delineated in the appended claims. In the following examples,all parts and percentages are by weight unless otherwise specified.

IV. EXAMPLES

Described below is a basic silicone pressure sensitive adhesive preparedwithout the alkylmethylsiloxane waxes as called for by the presentinvention. This is indicated in the Examples as the control sample,Control PSA. From this basic formulation, examples were prepared byadding various alkylmethylsiloxane waxes, testing them and tabulatingthe results.

The basic adhesive formulation included two main components: a silicateresin and a silicone fluid. The Control PSA, was made from a variouscombination of Resins A-1, A-2 and trimethylsiloxy endblockedpolydimethylsiloxane (PDMS) Fluid A as described below.

For the following examples, Resin A-1 is a xylene solution of a resinouscopolymeric siloxane prepared from 45 parts of sodium silicate (41.6°Be) and 20 parts of Me₃ SiCl (Me═CH₃) according to the method of U.S.Pat. No. 2,676,182 to Daudt, et al., which is hereby incorporated byreference, and contains Me₃ SiO_(1/2) units and SiO_(4/2) units in aratio of approximately 0.75:1.0, and has a non-volatile content (N.V.C.)of typically about 69-71%, an acid number in the range of 0.3 to 1.4, adynamic viscosity value in the range of 10-14 centipoise at 25° C. at60% N.V.C. in xylene solution, and a silicon-bonded hydroxyl content ofabout 2.5 weight percent based on a 100% N.V.C.

Resin A-2 is devolatilized Resin A-1 (100% non-volatile content).

PDMS Fluid A is a homogeneous mixture of a hydroxyl-endblockedpolydimethylsiloxane having a number-average molecular weight ofapproximately 40,000, along with minor amounts of cyclicpolydimethylsiloxane having degrees of polymerization between 4 and 30,the mixture having a dynamic viscosity between 12,000 and 15,000centipoise as measured using a Brookfield Viscometer Model HAF withspindle #3 at 10 RPM's.

The Control PSA was prepared by homogeneously mixing 24.1 parts byweight of Resin A-2, 39.8 parts by weight xylene, and 36.1 parts byweight PDMS Fluid A. The mixture was then heated to 115° C. andanhydrous ammonia was passed through the mixture at a rate of 11ml/min/lb of non-volatile component of the mixture for approximately 4hours. To endcap the mixture, hexamethyldisilazane was then mixed at a3:1 mole ratio of endblocking triorganosilyl to total silicon-bondedhydroxyl radicals present in the resin copolymer andpolydiorganosiloxane, and the mixture was allowed to react for 3 hoursat 95°-100° C. The mixture was then heated to 140° C. and maintained at140° C. under reflux conditions for 3 hours to remove condensationwater.

The physical properties of tack, release, adhesion and shear are setforth in Table 1. The methods for measuring these values are describedhere. Although the following Examples utilize different chemicalcompositions, the same testing methods were followed for all samples.Measurements were obtained by testing a one inch wide polyester tapehaving a silicone pressure sensitive adhesive thereon. The adhesiveswere prepared by blending about 1.0 percent to 15.0 percent by weight ofan alkylmethylsiloxane wax with between 99.0 and 85.0 percent by weightof silicone pressure sensitive adhesive and casting it to about a 2 milthickness on "SCOTCH-PAK" 1022 Release Liner, a polyester film coatedwith a release coating available from the 3M Company, St. Paul, Minn.,owner of the trademark "SCOTCH-PAK", 3M Company Health Care SpecialtiesDiv. St. Paul, Minn. After coating, a "MYLAR" polyester film was adheredto each casted alkylmethylsiloxane wax-containing sample with a 4 lb.rubber transfer roller.

The laminate is then cut into one-inch wide strips with the use of aone-inch tape specimen cutter received from the Pressure Sensitive TapeCouncil, 1800 Pickwick Ave., Glenview, Ill. 60025-1357.

The tack values were measured using a "POLYKEN" Probe Tack Tester,Series 400, made by Testing Machines, Inc., Amityville, N.Y. The speedof the probe was controlled at 0.5 cm/second and dwell time was at 0.5seconds. Tack values of between about 50 and about 800 grams/cm² areconsidered acceptable.

The release values were obtained by stripping the tape from the"SCOTCH-PAK" 1022 Release Liner at a rate of 40 inches/minute at anangle of 180° while attached to a tensile testing machine. An averagevalue over the entire length of the liner was recorded. Release valuesof less than 50 gm/cm are considered acceptable.

The adhesion values were obtained as follows. The tapes having thesilicone pressure sensitive adhesive composition thereon were adhered toa stainless steel panel with a 4 lb. roller and allowed to rest for 20minutes. The adhesion measurements were obtained by stripping each tapefrom the panel at a rate of 12 inches/minute at an angle of 180° whileattached to a tensile testing machine. Desirable values range betweenabout 100 and about 2000 gm/cm.

Shear values were measured by cutting three strips of the preparedlaminates 2.5 cm wide and 7.5 cm in length. A 3.5 cm wide by 5.0 cm longstrip of Mylar, a polyester film available from DuPont de Nemours, E. I.Co., Wilmington, Del. also owner of the trademark "Mylar", is applied tothe adhesive strip so as to provide an overlap of 2.5 cm in thelengthwise direction. These are laminated using a 4 lb. rubber rollerand allowed to equilibrate for 20 minutes. The specimen is mounted intothe jaws of an Instron Model 1122 Tensometer, available from InstronCorporation, and pulled at a speed of 0.5 cm/min. and the peak loadrequired to shear and separate the laminate is recorded in Kg/6.25 cm².Desirable values range between 4 and 20 kg/6.25 cm².

Dynamic viscosities (n*) measured in poise and elastic storage moduli(G') measured in dynes/cm² were measured on the adhesive compositionsusing a Rheometrics® Dynamic Spectrometer, Model RDS2 available fromRheometrics, Piscataway, N.J., and running a temperature sweep on 4 gramsamples of 1 mm thickness, and operating the tester at a frequency of100 radians/sec and a 1% strain using a 50 mm cup and plate. Desirabledynamic viscosities (n*) should be less than or equal to 800 poise at orbelow 200° C.

Elastic storage modulus (G') is directly related to die swell andelastic memory. The higher the die swell, the smaller the size of anorifice required for a given coating thickness. Therefore, the lower theelastic storage modulus, the better, as it is then easier to coat onto asubstrate. Tests similar to those run in these examples are described inASTM 4065-82. Desirable storage modulus values should be less than45,000 dynes/cm² at or below 200° C.

Hereinbelow, the term "pressure sensitive adhesive" may be abbreviatedto "PSA".

EXAMPLE 1

Adhesive formulations combining Control PSA and varying amounts ofalkylmethylsiloxane waxes were prepared as set forth in Tables 1-2. Asshown in Table 1, these adhesive preparations were evaluated forphysical properties of tack, release, adhesion and shear. Tack valuesranged between 5 and 521 gm/cm², and 11 of 12 samples were well withinthe acceptable range of 50 to 800 gm/cm². Release values ranged between2.1 and 17.3 gm/cm, and all samples were within the acceptable range ofless than or equal to 50 gm/cm. Adhesion values for our samples rangedbetween 186 and 790 gm/cm. All samples were within the acceptable rangeof 100-2000 gm/cm. Shear values ranged from 5.1 to 15.3 kg/6.25 cm² andwere within the acceptable range of 4 to 20 kg/6.25 cm². These resultsshow that the addition of siloxane waxes to the PSA's does not adverselyaffect the physical properties of the PSA's.

Decreased dynamic viscosity values are desirable to improve coatabilitywithout solvents. Each sample containing the alkylmethylsiloxane waxdemonstrated the desirable result of decreasing dynamic viscosity incomparison to the Control PSA.

                                      TABLE 1                                     __________________________________________________________________________    Physical Data For Control PSA With Alkylmethylsiloxane Waxes                                Wax Wt %                                                                              Thick                                                                             Tack Release                                                                            Adhesion                                                                           Shear                                Wax Product   MP  Wax (mils)                                                                            (g/cm.sup.2)                                                                       (g/cm)                                                                             (g/cm)                                                                             Kg/6.25 cm.sup.2                     __________________________________________________________________________    Control PSA   --  0   2   377  3.2  573  15.8                                 (C.sub.18 H.sub.32 SiO).sub.4                                                               38° C.                                                                      1% 3.5 366  2.9  783  13.7                                 (C.sub.18 H.sub.32 SiO).sub.4                                                               38° C.                                                                      5% 3   521  5.7  495  13.2                                 (C.sub.18 H.sub.32 SiO).sub.4                                                               38° C.                                                                     10% 2.5 --   8.6  186  --                                   (C.sub.18 H.sub.32 SiO).sub.4                                                               38° C.                                                                     15% 4.3 189  5    611  11.8                                 (C.sub.20 H.sub.34 SiO).sub.5                                                               53° C.                                                                      1% 3   210  2.1  790  14.8                                 (C.sub.20 H.sub.34 SiO).sub.5                                                               53° C.                                                                      5% 4.5 163  2.5  621  13.5                                 (C.sub.20 H.sub.34 SiO).sub.5                                                               53° C.                                                                     10% 2.5 --   10.3 397  --                                   (C.sub.20 H.sub.34 SiO).sub.5                                                               53° C.                                                                     15% 6.5 154  17.2 560  5.1                                  (C.sub.24-28 H.sub.49-57 MeSiO).sub.5                                                       56° C.                                                                      1% 4   367  2.2  772  15.3                                 (C.sub.24-28 H.sub.49-57 MeSiO).sub.5                                                       56° C.                                                                      5% 3.5 109  2.9  654  14.5                                 (C.sub.24-28 H.sub.49-57 MeSiO).sub.5                                                       56° C.                                                                     10% 2.5 --   12   438  --                                   (C.sub.24-28 H.sub.49-57 MeSiO).sub.5                                                       56° C.                                                                     15% 3.5 601  17.3 328  5.8                                  Me.sub.3 SiO(C.sub.18 H.sub.37 MeSiO).sub.54 --                                             48° C.                                                                      1% 3   202  3.2  639  14.6                                 (MeHSiO).sub.18 SiMe.sub.3                                                    Me.sub.3 SiO(C.sub.18 H.sub.37 MeSiO).sub.54 --                                             48° C.                                                                      5% 3.5  5   14.4 513  9.1                                  (MeHSiO).sub.18 SiMe.sub.3                                                    Me.sub.3 SiO(C.sub.18 H.sub.37 MeSiO).sub.54 --                                             48° C.                                                                     10% 2.5 --   7.5  200  --                                   (MeHSiO).sub.18 SiMe.sub.3                                                    Me.sub.3 SiO(C.sub.18 H.sub.37 MeSiO).sub.54 --                                             48° C.                                                                     15% 3    75  2.6  522  13.4                                 (MeHSiO).sub.18 SiMe.sub.3                                                    __________________________________________________________________________

As shown in Table 2, the Rheological properties of Elastic Modulus (G')and Dynamic Viscosity (n*) were evaluated for the various adhesiveformulations at temperatures ranging from 50° C. to 200° C. The valueswere measured at temperatures utilized in the hot-melt process, a lowboundary of 100° C. and a high temperature of 200° C., and wereacceptable for both properties. The alkylmethylsiloxane wax additivelowered the elastic modulus values compared to the Control PSA at bothboundary temperatures.

The results displayed in Table 2 illustrate the overall desirable resultof lowered dynamic viscosity of the Control PSA by the addition of thealkylmethylsiloxane waxes, in comparison to the Control PSA without wax,at temperatures of 50° C., 100° C., 150° C. and 200° C. Reduced dynamicviscosity was achieved for all wax-containing samples at or below 200°C.

                                      TABLE 2                                     __________________________________________________________________________    Rheological Data For Control PSA With Alkylmethylsiloxane Waxes At            50° C.-200° C.                                                  __________________________________________________________________________                  Wax WT %                                                                             50° C.                                                                           100° C.                                 Wax Product   MP  Wax                                                                              G'   N*   G'   N*                                        __________________________________________________________________________    Control PSA   --  -- 6.5E + 5                                                                           6.7E + 3                                                                           3.5E + 5                                                                           4.1E + 3                                  (C.sub.18 H.sub.32 SiO).sub.4                                                               38° C.                                                                      1%                                                                              3.5E + 5                                                                           4.1E + 3                                                                           1.0E + 5                                                                           1.5E + 3                                  (C.sub.18 H.sub.32 SiO).sub.4                                                               38° C.                                                                      5%                                                                              2.6E + 5                                                                           3.1E + 3                                                                           7.2E + 4                                                                           1.0E + 3                                  (C.sub.18 H.sub.32 SiO).sub.4                                                               38° C.                                                                     10%                                                                              5.5E + 5                                                                           5.9E + 3                                                                           1.9E + 5                                                                           1.8E + 3                                  (C.sub.18 H.sub.32 SiO).sub.4                                                               38° C.                                                                     15%                                                                              1.5E + 5                                                                           1.9E + 3                                                                           4.5E + 4                                                                           6.8E + 2                                  (C.sub.20 H.sub.34 SiO).sub.5                                                               53° C.                                                                      1%                                                                              4.8E + 5                                                                           5.2E +  3                                                                          1.7E + 5                                                                           2.2E + 3                                  (C.sub.20 H.sub.34 SiO).sub.5                                                               53° C.                                                                      5%                                                                              2.6E + 5                                                                           3.1E + 3                                                                           8.9E + 4                                                                           1.3E + 3                                  (C.sub.20 H.sub.34 SiO).sub.5                                                               53° C.                                                                     10%                                                                              4.9E + 5                                                                           5.4E + 3                                                                           2.2E + 5                                                                           3.0E + 3                                  (C.sub.20 H.sub.34 SiO).sub.5                                                               53° C.                                                                     15%                                                                              2.6E + 5                                                                           3.2E + 3                                                                           9.0E + 4                                                                           1.3E + 3                                  (C.sub.24-28 H.sub.49-57 MeSiO).sub.5                                                       56° C.                                                                      1%                                                                              4.0E + 5                                                                           4.5E + 3                                                                           1.5E + 5                                                                           2.0E + 3                                  (C.sub.24-28 H.sub.49-57 MeSiO).sub.5                                                       56° C.                                                                      4%                                                                              1.8E + 5                                                                           2.3E + 3                                                                           5.1E + 4                                                                           7.9E + 3                                  (C.sub.24-28 H.sub.49-57 MeSiO).sub.5                                                       56° C.                                                                      5%                                                                              2.0E + 5                                                                           2.5E + 3                                                                           6.0E + 4                                                                           9.1E + 2                                  (C.sub.24-28 H.sub.49-57 MeSiO).sub.5                                                       56° C.                                                                     10%                                                                              4.2E + 5                                                                           4.7E + 3                                                                           1.4E + 5                                                                           1.9E + 3                                  (C.sub.24-28 H.sub.49-57 MeSiO).sub.5                                                       56° C.                                                                     15%                                                                              3.5E + 5                                                                           4.0E + 3                                                                           6.2E + 4                                                                           9.1E + 2                                  Me.sub.3 SiO(C.sub.18 H.sub.37 MeSiO).sub.54 --                                             48° C.                                                                      1%                                                                              2.7E + 5                                                                           3.2E + 3                                                                           8.5E + 4                                                                           1.2E + 3                                  (MeHSiO).sub.18 SiMe.sub.3                                                    Me.sub.3 SiO(C.sub.18 H.sub.37 MeSiO).sub.54 --                                             48° C.                                                                      4%                                                                              2.5E + 5                                                                           3.0E + 3                                                                           8.2E + 4                                                                           1.2E + 3                                  (MeHSiO).sub.18 SiMe.sub.3                                                    Me.sub.3 SiO(C.sub.18 H.sub.37 MeSiO).sub.54 --                                             48° C.                                                                      5%                                                                              3.6E + 5                                                                           4.1E + 3                                                                           1.3E + 5                                                                           1.7E + 3                                  (MeHSiO).sub.18 SiMe.sub.3                                                    Me.sub.3 SiO(C.sub.18 H.sub.37 MeSiO).sub.54 --                                             48° C.                                                                     10%                                                                              5.2E + 5                                                                           5.6E + 3                                                                           2.4E + 5                                                                           2.9E + 3                                  (MeHSiO).sub.18 SiMe.sub.3                                                    Me.sub.3 SiO(C.sub.18 H.sub.37 MeSiO).sub.54 --                                             48° C.                                                                     15%                                                                              9.1E + 4                                                                           1.3E + 3                                                                           2.6E + 4                                                                           4.2E +  2                                 (MeHSiO).sub.18 SiMe.sub.3                                                    __________________________________________________________________________                  Wax WT %                                                                             150° C.                                                                          200° C.                                 Wax Product   MP  Wax                                                                              G'   N*   G'   N*                                        __________________________________________________________________________    Control PSA   --  -- 1.3E + 5                                                                           1.8E + 3                                                                           4.0E + 4                                                                           9.3E + 2                                  (C.sub.18 H.sub.32 SiO).sub.4                                                               38° C.                                                                      1%                                                                              2.8E + 4                                                                           4.7E + 2                                                                           6.5E + 3                                                                           1.3E + 2                                  (C.sub.18 H.sub.32 SiO).sub.4                                                               38° C.                                                                      5%                                                                              1.5E + 4                                                                           2.9E + 2                                                                           3.4E + 3                                                                           7.3E + 1                                  (C.sub.18 H.sub.32 SiO).sub.4                                                               38° C.                                                                     10%                                                                              6.3E + 4                                                                           9.7E + 2                                                                           2.7E + 4                                                                           5.0E + 2                                  (C.sub.18 H.sub.32 SiO).sub.4                                                               38° C.                                                                     15%                                                                              8.0E + 3                                                                           1.6E + 2                                                                           2.8E + 3                                                                           5.9E + 1                                  (C.sub.20 H.sub.34 SiO).sub.5                                                               53° C.                                                                      1%                                                                              4.5E + 4                                                                           7.2E + 2                                                                           1.5E + 4                                                                           2.9E + 2                                  (C.sub.20 H.sub.34 SiO).sub.5                                                               53° C.                                                                      5%                                                                              1.6E + 4                                                                           3.0E + 2                                                                           6.1E + 3                                                                           1.2E + 2                                  (C.sub.20 H.sub.34 SiO).sub.5                                                               53° C.                                                                     10%                                                                              7.1E + 4                                                                           1.1E + 3                                                                           1.9E + 4                                                                           3.9E + 2                                  (C.sub.20 H.sub.34 SiO).sub.5                                                               53° C.                                                                     15%                                                                              2.0E + 4                                                                           3.8E + 2                                                                           4.8E + 3                                                                           9.6E + 1                                  (C.sub.24-28 H.sub.49-57 MeSiO).sub.5                                                       56° C.                                                                      1%                                                                              3.5E + 4                                                                           6.1E + 2                                                                           1.2E + 4                                                                           2.4E + 2                                  (C.sub.24-28 H.sub.49-57 MeSiO).sub.5                                                       56° C.                                                                      4%                                                                              7.2E + 3                                                                           1.2E + 2                                                                           5.9E + 3                                                                           1.2E + 2                                  (C.sub.24-28 H.sub.49-57 MeSiO).sub.5                                                       56° C.                                                                      5%                                                                              9.2E + 3                                                                           1.6E + 2                                                                           5.4E + 3                                                                           1.1E + 2                                  (C.sub.24-28 H.sub.49-57 MeSiO).sub.5                                                       56° C.                                                                     10%                                                                              3.9E + 4                                                                           5.9E + 2                                                                           9.4E + 3                                                                           1.9E + 2                                  (C.sub.24-28 H.sub.49-57 MeSiO).sub.5                                                       56°  C.                                                                    15%                                                                              1.6E + 4                                                                           1.6E + 2                                                                           4.1E + 3                                                                           8.5E + 1                                  Me.sub.3 SiO(C.sub.18 H.sub.37 MeSiO).sub.54 --                                             48° C.                                                                      1%                                                                              1.3E + 4                                                                           2.3E + 2                                                                           8.4E + 3                                                                           1.6E + 2                                  (MeHSiO).sub.18 SiMe.sub.3                                                    Me.sub.3 SiO(C.sub.18 H.sub.37 MeSiO).sub.54 --                                             48° C.                                                                      4%                                                                              1.2E + 4                                                                           1.6E + 2                                                                           8.1E + 3                                                                           1.6E + 2                                  (MeHSiO).sub.18 SiMe.sub.3                                                    Me.sub.3 SiO(C.sub.18 H.sub.37 MeSiO).sub.54 --                                             48° C.                                                                      5%                                                                              3.5E + 4                                                                           4.1E + 2                                                                           1.4E + 4                                                                           2.7E + 2                                  (MeHSiO).sub.18 SiMe.sub.3                                                    Me.sub.3 SiO(C.sub.18 H.sub.37 MeSiO).sub.54 --                                             48° C.                                                                     10%                                                                              8.9E + 4                                                                           1.2E + 3                                                                           2.9E + 4                                                                           5.0E + 2                                  (MeHSiO).sub.18 SiMe.sub.3                                                    Me.sub.3 SiO(C.sub.18 H.sub.37 MeSiO).sub.54 --                                             48° C.                                                                     15%                                                                              5.6E + 3                                                                           9.8E + 1                                                                           5.9E + 3                                                                           1.1E + 2                                  (MeHSiO).sub.18 SiMe.sub.3                                                    __________________________________________________________________________     G' = Elastic storage modulus measured in dynes/cm.sup.2.                      N* = Dynamic viscosity measured in poise.                                

Therefore, the objects of this invention have been met by addingalkylmethylsiloxane wax to a hot-melt pressure sensitive siliconeadhesive. By decreasing the dynamic viscosity of the adhesive,coatability was improved, which allows for less waste duringmanufacturing processes. Thus, there is provided in accordance with thepresent invention, a composition for an improved pressure sensitiveadhesive, a method for coating the adhesive, and devices which includethe pressure sensitive adhesive composition.

While our invention has been described in terms of a specificembodiment, it will be appreciated that other embodiments could readilybe adapted by one skilled in the art. Accordingly, the scope of ourinvention is to be limited only by the following claims.

We claim:
 1. A matrix transdermal drug delivery device for a bioactiveagent, comprising:(a) a backing substrate; (b) a matrix atop at leastportions of said backing substrate, said matrix containing a hot-melt,silicone pressure sensitive adhesive composition containing a mixture of(i) a silicate resin, (ii) a silicone fluid, and (iii) analkylmethylsiloxane wax which decreases dynamic viscosity of theadhesive composition at temperatures ranging from 50° C. to about 200°C. and said adhesive including compositions selected from the groupconsisting of drugs, excipients, co-solvents, enhancers, and mixturesthereof where the adhesive is compatible with said drugs, excipients andco-solvents and enhancers, said hot-melt, silicone pressure sensitiveadhesive being disposed within said matrix; and (c) a release linercontacted on the matrix.
 2. The matrix transdermal drug delivery deviceof claim 1, wherein the drugs include drugs selected from the groupconsisting of cardiovascular agents, antiarrhythmic agents, antianginalagents, antibiotics, antifungals, antimicrobials, antihypertensives,analgesics, local anesthetics, contraceptives, hormonal supplements,anti-smoking agents, appetite suppressants, hypnotics, anxiolytics, andmixtures thereof.
 3. The matrix transdermal drug delivery device ofclaim 1, wherein the matrix is between about 1 and about 15 mils thick.4. The matrix transdermal drug delivery device of claim 1, wherein theco-solvents and excipients are selected from the group consisting offatty acid esters, polyols, surfactants, terpenes, glycerol esters,polyethylene glycol esters, amides, sulfoxides, lactams, nonionicsurfactants, sorbitan esters, and mixtures thereof.
 5. A reservoirtransdermal drug delivery device, comprising:(a) a backing substrate;(b) a reservoir attached to at least portions of the backing substrate,said reservoir containing compositions selected from the groupconsisting of drugs, excipients, co-solvents, enhancers, and mixturesthereof; (c) a hot-melt silicone pressure sensitive adhesive compositioncontaining a mixture of (i) a silicate resin, (ii) a silicone fluid, and(iii) an alkylmethylsiloxane wax which decreases dynamic viscosity ofthe adhesive composition at temperatures ranging from about 50° C. toabout 200° C. coated on top of the reservoir and portions of the backingsubstrate not covered by the reservoir; and (d) a release liner attachedto the silicone pressure sensitive adhesive.
 6. The reservoirtransdermal drug delivery device of claim 5, wherein the drugs includedrugs selected from the group consisting of cardiovascular agents,antiarrhythmic agents, antianginal agents, antibiotics, antifungals,antimicrobials, antihypertensives, analgesics, local anesthetics,contraceptives, hormonal supplements, anti-smoking agents, appetitesuppressants, hypnotics, anxiolytics, and mixtures thereof.
 7. Thereservoir transdermal drug delivery device of claim 5, wherein theco-solvents and excipients are selected from the group consisting offatty acid esters, polyols, surfactants, terpenes, glycerol esters,polyethylene glycol esters, amides, sulfoxides, lactams, nonionicsurfactants, sorbitan esters, and mixtures thereof.
 8. The reservoirtransdermal drug delivery device of claim 5, wherein the siliconepressure sensitive adhesive is between about 1 and about 15 mils thick.9. The reservoir transdermal drug delivery device of claim 5, furthercomprising a rate controlling membrane, said rate controlling membranebeing positioned over said reservoir and sealing the reservoir betweenthe backing substrate and the rate controlling membrane.
 10. Thereservoir transdermal drug delivery device of claim 5, wherein thereservoir is a liquid reservoir.
 11. The reservoir transdermal drugdelivery device of claim 5, wherein the reservoir is a solid statereservoir.
 12. The matrix transdermal drug delivery device of claim 1,wherein the alkylmethylsiloxane wax is selected from the groupconsisting of waxes having the following formulations:

    (RMeSiO).sub.x

wherein R is C_(n) H_(1n+1), Me is CH₃, 14≦n≦28, and X is an integerfrom 4 to 6;

    RMe.sub.2 SiOSiMe.sub.2 R

wherein Me is CH₃, R is C_(n) H_(2n+1), and n≧18;

    RMe.sub.2 SiOSiMe.sub.3

wherein Me is CH₃, R is C_(n) H_(2n+1), and n≧24;

    RMeSi(OSiMe.sub.3).sub.2

wherein Me is CH₃, R is C_(n) H_(2n+1), and n≧24;

    Me.sub.3 SiO(RMeSiO).sub.x (R'MeSiO).sub.y SiMe.sub.3

wherein Me is CH₃, R is C_(n) H_(2n+1), and n≧18, R' is H or C_(n)H_(2n+1) and n≧1, when R' is H or CH₃ then the ratio of X:Y is greaterthan 1:3;

    RSiO.sub.3/2

wherein R is C_(n) H_(2n+1), and n≧1; and mixtures thereof.
 13. Thematrix transdermal drug delivery device of claim 1, wherein thealkylmethylsiloxane wax is present in an amount between about 1.0 andabout 25.0 percent by weight based on total adhesive composition weight.14. The matrix transdermal drug delivery device of claim 1, wherein thealkylmethylsiloxane wax is present in an amount between about 5 percentand about 15 percent by weight based on total adhesive compositionweight.
 15. The matrix transdermal drug delivery device of claim 1,wherein the silicone pressure sensitive adhesive containing thealkylmethylsiloxane wax has a dynamic viscosity less than or equal to800 poise at a temperature equal to or below 200° C.
 16. The matrixtransdermal drug delivery device of claim 1, wherein the hot-meltsilicone pressure sensitive adhesive composition contains(a) betweenabout 30 and about 70 percent by weight silicate resin; (b) betweenabout 22 and about 60 percent by weight silicone fluid; and (c) betweenabout 1.0 and about 25 percent by weight based of an alkylmethylsiloxanewax, all weight percents being based on total composition weight. 17.The reservoir transdermal drug delivery device of claim 5, wherein thealkylmethylsiloxane wax is selected from the group consisting of waxeshaving the following formulations:

    (RMeSiO).sub.x

wherein R is C_(n) H_(2n+1), Me is CH₃, 14≦n≦28, and X is an integerfrom 4 to 6;

    RMe.sub.2 SiOSiMe.sub.2 R

wherein Me is CH₃, R is C_(n) H_(2n+1), and n≧18;

    RMe.sub.2 SiOSiMe.sub.3

wherein Me is CH₃, R is C_(n) H_(2n+1), and n≧24;

    RMeSi(OSiMe.sub.3).sub.2

wherein Me is CH₃, R is C_(n) H_(2n+1), and n≧24;

    Me.sub.3 SiO(RMeSiO).sub.x (R'MeSiO).sub.y SiMe.sub.3

wherein Me is CH₃, R is C_(n) H_(2n+1), and n≧18, R' is H or C_(n)H_(2n+1) and n≧1, when R' is H or CH₃ then the ratio of X:Y is greaterthan 1:3;

    RSiO.sub.3/2

wherein R is C_(n) H_(2n+1), and n≧1; and mixtures thereof.
 18. Thereservoir transdermal drug delivery device of claim 5, wherein thealkylmethylsiloxane wax is present in an amount between about 1.0 andabout
 25. 0 percent by weight based on total adhesive compositionweight.
 19. The reservoir transdermal drug delivery device of claim 5,wherein the alkylmethylsiloxane wax is present in an amount betweenabout 5 percent and about 15 percent by weight based on total adhesivecomposition weight.
 20. The reservoir transdermal drug delivery deviceof claim 5, wherein the silicone pressure sensitive adhesive containingthe alkylmethylsiloxane wax has a dynamic viscosity less than or equalto 800 poise at a temperature equal to or below 200° C.
 21. Thereservoir transdermal drug delivery device of claim 5, wherein thehot-melt silicone pressure sensitive adhesive composition contains(a)between about 30 and about 70 percent by weight silicate resin; (b)between about 22 and about 60 percent by weight silicone fluid; and (c)between about 1.0 and about 25 percent by weight based of analkylmethylsiloxane wax, all weight percents being based on totalcomposition weight.